The present invention relates to a laser pointer, especially to a laser pointer that projects a single point, a line with controllable length, or an ellipse image, a circle image or an image of other patterns such as Lissajous pattern with controllable pattern and size just in time.
Now laser pointers available on the market project a single spot. Users take the laser pointer to emit a laser beam that forms a laser spot as an indicator. However, the single spot is unable to cover a certain range of information so that the user needs to wave (or shake) the laser point for indicating or emphasizing certain area of the image or part of the object. By movement of the laser spot, a certain area is indicated. Yet such movement is difficult to make the laser spot fall on the position required precisely and cause inconvenience of users. Although such waving may draw audiences' attention, the accuracy of the indication is poor and the audience may have bad feelings.
In order to overcome the above disadvantages of the conventional laser pointer with single spot, some non-spot laser pointers are available now. Refer to U.S. Pat. No. 5,450,148, a laser pointer is disposed with a cylindrical lens so as to project a linear image instead of a single spot but the length of the linear image is unable to be adjusted. Refer to U.S. Pat. No. 5,938,308, a laser pointer is disposed with a holographic element or a diffractive optical element so as to project non-spot laser images. By change of the holographic element, a different laser image is projected. Yet by the diffractive optical element, size of the laser image is unable to be changed according to the user's needs. Thus when the laser image is unable to label or cover a certain area, the user still need to wave his hand for emphasis. Moreover, although the pattern of the image projected by the diffractive optical element can be changed, the size is still fixed. Furthermore, the laser pointer with the diffractive optical element has other problems such as low optical efficiency and manufacturing difficulties that have negative effects on the applications.